i have one problem , i am working on simple project . In this project i use 7 seg display and keypad but my problem is that key pade one pin is connected to the 7 seg common pin and another pin uconnected to the Controller gpio pin through transistor so cant take judgemet that it is work or not.

i tried with DE-multiplexer but i am not able to configure it properly . i getting problem with demux width connection(selector pin) , which is taking value from digital input pin and for more output it need bus connection i don't know how to provide bus connection . so i use 1x2 demux it need only one select line and changing demux output pin properly . but i want to control demux output in run time not by physical gpio pin . then i use digital constant to change demux selector value but it won't solve my problem .